Sorry about the HTML mail attempt. They won't let me turn off automatic
HTML on our server. I think this client will avoid the problem.

While researching a NAT pool exhaustion problem, I came across a number
of strange NAT pairs. Essentially, addresses in the global pool are
turning up on the local side, mapped to a different address in the
outside pool.

They are usually paired to the next address in sequence, but there are a
few exceptions.